FR3099249A1 - Drill core analysis method and device - Google Patents

Abstract

The invention relates to a method for analyzing a drill core (3), characterized in that it comprises the following steps: carrying out a three-dimensional modeling of the drill core (3) by photogrammetry using high resolution imaging means (8) and hyperspectral imaging means (8); and perform an analysis of the mineralogical composition of the surface of the drill core (3) using the light spectrum, measured by the hyperspectral imaging means (8), emitted by the drill core (3) by luminescence in response to lighting emitted by lighting means (7). The invention also relates to a drill core analysis device (1) capable of implementing the drill core analysis method according to the invention. Figure to be published with the abstract: Figure 1

Description

Method and device for analyzing drill core

The present invention relates to the field of drill cores, and relates in particular to a method and a device for analyzing drill cores.

Drill cores, or geological cores, are globally cylindrical objects extracted during drilling, which provide access to geological information buried by the accumulation of several kilometers of sediment. Obtaining a geological core is a very expensive operation and can only be done once per area of interest. The geological information collected during control and exploration drilling is of crucial interest, preserving it over time to preserve the information for future studies is one example, among many others, to demonstrate the interest of these specific objects. The preservation of drill cores and the information they contain is therefore essential.

Core shacks, which are places where drill cores are stored, are technically complex infrastructures that are costly to set up. Indeed, it is necessary to continuously control the temperature, the pressure, the hygrometry and the composition of the air of the core shack to limit the degradation of the cores stored in it (which is rarely the case and justifies the development of preservation methods).

In addition, the many analyses, often destructive, subsequently carried out on the drill cores contribute to maintaining an irreversible loss of the information contained in the drill cores.

In addition, today, drill cores are taken extensively, and photographed at scales and resolutions insufficient to use these documents as "digital lithological samples". It appears necessary, given their interest, to develop a reliable means of saving these lithological data at a sufficient resolution to be able to subsequently carry out the majority of the analyzes in a non-destructive manner.

As part of the characterization of minerals contained in drill cores, several technologies have been developed using X-ray emission sources, the high intensity of these X-rays allowing high-resolution chemical characterization. However, these X-ray technologies have a major drawback, which is that of depending on a radioactive source and requiring associated protections (for example, laboratory work with dosimeters, which cannot be transposed to the field).

PCT international application WO2010151490A1 describes a device for analyzing drill core using an X-ray scanner and cameras, the X-ray scanner being used to characterize the core minerals and the cameras being used to produce a virtual carrot. However, the analysis carried out by this existing device is destructive, since the drill core must first be cut into two longitudinal parts using a jet of fluid. In addition, the X-ray scanner used to characterize the core is a radioactive source requiring associated protections. Moreover, this device does not make it possible to carry out a high-resolution analysis.

The present invention aims to solve the drawbacks of the prior state of the art, by proposing a method and a device for analyzing drill core using three-dimensional modeling by photogrammetry and analysis of mineralogical composition. by hyperspectral imagery, which makes it possible to save the lithological data of the drilling core at a sufficient resolution to be able to subsequently carry out the majority of the analyzes in a non-destructive manner.

The subject of the present invention is therefore a method for analyzing a drill core, characterized in that it comprises the following steps: carrying out a three-dimensional modeling of the drill core by photogrammetry using means of high-resolution imaging and hyperspectral imaging means; and carrying out an analysis of the mineralogical composition of the surface of the drill core using the light spectrum, measured by the hyperspectral imaging means, emitted by the drill core by luminescence in response to lighting emitted by means lighting.

Thus, the method according to the present invention allows mineral recognition combined with a three-dimensional (3D) reconstruction of the drill core.

The mineralogical analysis carried out by the method of the present invention is non-destructive (no grinding, sampling or chemical processes, for example), which makes it possible to save the information contained in the drill core.

High-resolution imaging means means imaging means making it possible to carry out macroscopic imaging with a minimum resolution of 20 megapixels (beyond the 1:1 ratio).

The high-resolution imaging means make it possible to produce a high-resolution 3D model of the drill core by photogrammetry, and, at the same time, the hyperspectral imaging means make it possible to produce a hyperspectral 3D model of the drill core by photogrammetry , the high-resolution 3D model and the hyperspectral 3D model being then superimposed in post-processing.

The high-resolution imaging means and the hyperspectral imaging means thus allow photorealistic 3D digital scanning of the drill core at a sufficiently fine resolution to allow subsequent in-depth study of the drill core (with a resolution, preferably, between 10 and 100 µm).

The 3D digital model produced has a higher level of detail than that of an observation under a magnifying glass during a conventional description, the magnification obtained making it possible to analyze images whose pixel size is, preferably, of the order of 10 µm, the interest being to be able to carry out on screen a work of description even more detailed than a traditional description.

To create a usable digital document, the carrot is modeled in high-resolution 3D using the photogrammetry technique. This technique, based on the principle of stereoscopic vision, aims at the three-dimensional reconstruction of an object from photographs taken from different angles. This technique, which uses triangulation algorithms, makes it possible to identify the common pixels between the different photographs to reposition them relative to each other in a cloud of photogrammetric points. It is then possible to reconstruct a 3D interpolation model between these different points.

During photogrammetry, it is essential to guarantee the quality of the shot to optimize the detection of homologous points and sufficient overlap between the different photographs, an optimal shot making it possible to work with a minimum of photographs while maintaining quality data.

Preferably, the photogrammetry technique is optimized using a process of focus stacking (from the Anglo-Saxon expression "focus stacking") which makes it possible to combine several images whose focal plane varies, to result in an image with greater depth of field than a single image.

Thus, the 3D modeling of the drill core makes it possible to keep a photorealistic digital version of the drill core so as to save the information it contains.

The analysis of the mineralogical composition of the drill core is based on the principle of spectroscopy, i.e. the study of the emission spectrum of a mineral species compared to a known source to extract qualitative information about the composition of certain minerals (majority and traces), databases of the reflectivity of different mineral species making it possible to identify minerals from the spectrum emitted.

The minerals contained in the drill core being luminescent, the luminescence of these minerals, when they are illuminated by the lighting means, is thus used to characterize the mineralogical composition of the drill core, the hyperspectral imaging means allowing to capture the light spectrum emitted, by luminescence, by the minerals on the surface of the drill core.

The luminescence is conditioned by the nature and the organization in space of the excited atoms. Each mineral having a unique chemical composition and a unique crystalline system (“cage” corresponding to an arrangement of atoms between them), the luminescence is therefore different for each mineral species.

Luminescence is the physical property of matter to emit an electromagnetic wave when subjected to radiation. The luminescence of a mineral depends on the interactions between electromagnetic waves (in this case, a light wave) and the atoms that make up the mineral. These interactions result in electronic exchanges within the atoms of the crystal lattice, producing a secondary electromagnetic wave. It is thus possible to obtain a characterization of the excited element by observing and measuring the light spectrum emitted under the effect of an energetic stimulation.

All chemical elements possess natural luminescence properties. In geosciences, it is qualified as intrinsic when it depends on the impurities present in the crystal lattice. In cathodoluminescence, however, some research points out that the majority of the signal (or the absence of signal) is caused by trace elements and would therefore be extrinsic. These elements belong to three groups according to their behavior with respect to electrical excitation, the activating, sensitizing and inhibiting elements:

- The activating elements are elements which accentuate the initial luminescence. It should be noted that beyond a certain concentration (inhibitory concentration), the luminescence decreases until extinction. Mn ²⁺ (manganese) is one of the activating ions commonly encountered in geological media.

- The sensitizing elements do not necessarily have luminescent properties strictly speaking, but they can absorb part of the energy received and transmit it to activating elements, thus increasing the intensity of their luminescence. For example, the luminescence of a calcite crystal caused by Mn ²⁺ ions can be intensified by the presence of Pb ²⁺ (lead) ions.

- The inhibiting elements can totally or partially trap the energy absorbed by the activating ions, thus causing a reduction in luminescence which can go as far as extinction.

It is difficult to draw up an exhaustive list of elements with respect to their behavior because this can vary according to the host mineral and the concentration of trace elements. For example, the Fe ³⁺ ion (iron) is an inhibitor in certain minerals, such as carbonates, but can be an activator in others, such as feldspars for example.

The optical properties of the mineral also have an impact on the luminescence, and more particularly the refractive index, which itself depends on the crystalline system in which the mineral grows. Three main groups of minerals can be identified:

- The first group includes minerals crystallizing in the cubic system, such as pyrite and galena for example. The refractive index, for these minerals, is dependent on their orientation, so there is a multitude of absorption spectra for each mineral belonging to this category.

- The second group includes minerals crystallizing in the trigonal, hexagonal and tetragonal system. They are anisotropic uniaxial minerals (birefringent), that is to say that their reflectivity depends on the axes of symmetry of the crystal and on the section concerned. If the section is parallel to the basal section, the optical properties are identical to those of an isotropic (monorefringent) mineral. For all other sections, the reflectivity depends on the orientation of the crystal.

- The third group comprises all the other minerals.

The luminescence of the minerals of a drill core is in the visible but also in spectral ranges outside the visible, it is therefore necessary to use hyperspectral imaging means to detect the entire spectrum emitted by the drill core . Thus, hyperspectral imaging means make it possible to detect the light spectrum of minerals in the visible but also in the infrared.

The means of hyperspectral imaging thus make it possible to identify different mineral phases of similar chemical composition and which are under-exploited in classical geology.

According to a particular characteristic of the present invention, the three-dimensional modeling is a textured three-dimensional modeling.

Thus, during the 3D modeling of the drill core using high-resolution imaging means and hyperspectral imaging means, a texture is added to the 3D model of the drill core, said texture making it possible to represent the relief on the surface of the drill core.

To do this, an additional texturing algorithm is implemented, said algorithm making it possible to texture the 3D model by mapping the other photographic pixels onto the 3D model. The result is a photorealistic textured 3D model of the drill core.

The presence of a texture on the 3D model thus makes it possible to subsequently carry out a detailed study of the sedimentary and tectonic structures, etc.

According to a particular characteristic of the present invention, the analysis of the mineralogical composition of the surface of the drill core comprises the comparison of the light spectrum measured by the hyperspectral imaging means with a database of predefined light spectra, and the determination of the mineral species present on the surface of the drill core using said comparison.

Thus, the predefined luminous spectra database contains all the existing hyperspectral data concerning the luminescence of different mineral species. The light spectrum detected by the hyperspectral imaging means can thus be compared with the data contained in said database in order to determine which mineral species make up the drill core. This implies cross-referencing the data acquired for each mineral at each wavelength using recognition algorithms. These mathematical learning systems are called neural networks.

The method according to the present invention thus allows the qualification of the minerals present on the surface of the drill core.

According to a particular characteristic of the present invention, the analysis of the mineralogical composition of the surface of the drill core further comprises the determination of the quantity of each mineral species present on the surface of the drill core.

Thus, the analysis of the light spectrum detected by the hyperspectral imaging means also makes it possible to determine the quantity of each of the mineral species detected, by determining the number of common spectra, which allows a semi-quantitative analysis.

The method according to the present invention thus allows both qualitative and semi-quantitative analysis of minerals, of their polymorphs (same chemical formula but different mineralogical assembly), by identifying certain trace elements (concentration of the order of 100-1000 ppm or more).

According to a particular characteristic of the present invention, the lighting emitted by the lighting means is at least one of ultraviolet light, white light and monochromatic laser light.

Thus, the lighting means preferably comprise at least one white lamp and at least one ultraviolet (UV) lamp (whose wavelength is less than 400 nm).

The lighting means thus do not include any radioactive source.

An incident UV beam, preferably of different wavelengths, is used to illuminate the drill core so as to characterize its mineralogical composition using hyperspectral imaging means, the energy of said incident UV beam being sufficient to cause the minerals in the drill core to glow.

The lighting of the lighting means is preferably produced by an emission system by optical fiber calibrated in Bragg gratings, or a lamp calibrated in wavelength (preferably, visible spectrum, UV 365 nm, UV 254 nm, and other wavelengths in the UV or infrared) to select the properties of the incident beams. It should be noted that an equivalent laser emission system could also be used, without departing from the scope of the present invention.

The present invention also relates to a drill core analysis device, characterized in that it comprises: a drill core support configured to carry a drill core; illumination means configured to illuminate the drill core; high resolution imaging means configured to perform high resolution imaging of the drill core; hyperspectral imaging means configured to perform hyperspectral imaging of the drill core; a support for lighting and imaging means carrying the lighting means, the high-resolution imaging means and the hyperspectral imaging means; rotational displacement means configured to rotate one of the drill core and the lighting and imaging means support; means for moving in translation configured to move in translation one of the drill core and the support of lighting and imaging means; and control means configured to control the lighting means, the high-resolution imaging means, the hyperspectral imaging means, the rotational displacement means and the translational displacement means, so as to implement the drill core analysis method as described above.

The lighting and imaging means support is designed such that the lighting means, the high-resolution imaging means and the hyperspectral imaging means are oriented towards the drill core to be analyzed carried by the support. of drill core.

Thus, the means for moving in rotation and the means for moving in translation make it possible to move the drill core and/or the support of lighting and imaging means, so as to allow 3D modeling and characterization of the composition mineral of the entire lateral surface of the analyzed drill core.

The control means make it possible to control, automatically or semi-automatically, the other elements of the drill core analysis device, so as to allow the analysis of the entire lateral surface of the drill core over all the length of the drill core.

After each movement caused by the rotational movement means and the translational movement means, the drill core, illuminated by the lighting means, is imaged by the high-resolution imaging means and the hyperspectral imaging means, so as to subsequently carry out the 3D modeling by photogrammetry and the characterization of the mineralogical composition using the detected light spectrum.

Thus, the drill core analysis device makes it possible to digitally save the information contained on the surface of the drill core with a high resolution in order to be able to subsequently carry out the majority of the analyzes in a non-destructive manner.

According to a particular characteristic of the present invention, the hyperspectral imaging means comprise at least one hyperspectral camera.

Hyperspectral imaging, different from multispectral imaging or superspectral imaging, is a technology allowing the reading of a surface by a large number (preferably, greater than 100) of narrow spectral bands (preferably, lower or equal to 10 nm) and contiguous.

Unlike multispectral imaging, which selects only certain bands to be analyzed, hyperspectral imaging makes it possible to acquire a “continuous” spectrum. It is this property that allows high-precision detection by measuring fine spectral variations.

The acquisition of the continuous spectrum is carried out by the hyperspectral camera in a range of wavelengths corresponding to the visible and near infrared domains (preferably, from 400 to 1000 nm, and up to 2500 nm when several hyperspectral cameras are used).

Hyperspectral imaging thus makes it possible to detect the spectral response of each pixel of the sample analyzed over a wide spectrum according to bands with a thickness, preferably, of 10 nm.

The response thus obtained under UV light and natural light allows identification for each pixel of the mineralogical composition of the drill core.

According to a particular characteristic of the present invention, the high resolution imaging means comprise at least one of a high resolution camera and a high resolution camera such as the reflex type, preferably with a minimum resolution of 20 megapixels. The camera or high-resolution camera can be of the reflex type or of another type such as an industrial ATEX (ATmospheres EXplosives) camera, a Connected Card Camera Module, etc.

According to a particular characteristic of the present invention, the drill core analysis device further comprises a display device connected to the control means, said display device being configured to display the three-dimensional modeling and the analysis of the mineralogical composition of the forge core produced by the control means.

Thus, the display device allows the user to view the 3D model produced of the drill core, as well as the analysis results of the mineralogical composition of the drill core.

The drill core analysis device can also comprise a man-machine interface allowing the user to control the control means of the drill core analysis device.

According to a first embodiment of the present invention, the means for moving in rotation are configured to move the drill core in rotation, and comprise at least three parallel rotary cylinders arranged longitudinally in the drill core support and adapted to receiving thereon the drill core, at least one of the at least three rotary cylinders being able to be driven in rotation by a stepper motor.

Thus, rotation of the at least one driven rotary cylinder causes the drill core to rotate on the at least three cylinders, thereby acquiring the entire circumference of the drill core, so as to create the three-dimensional model.

Preferably, the driven rotating cylinder has a lower height than the other cylinders, the driven rotating cylinder thus being arranged under the drill core and the other cylinders being arranged on either side of the circumference of the drill core.

The stepping motor, controlled by the control means, makes it possible to rotate the driven rotary cylinder, which causes the rotation of the drill core on the rotary cylinders to allow the positioning of the drill core with respect to the lighting and imaging means, so as to allow three-dimensional scanning of the core by the high-resolution imaging means and the hyperspectral imaging means.

In this first embodiment, the drill core support, in which the at least three rotary cylinders are arranged, is preferably one-piece and in the form of a gutter, the rotary cylinders being mounted on bearings arranged in the support of the drill core. drill core.

A non-slip material, such as neoprene, rumble strip or silicone fabric, is preferably placed on each rotating cylinder, the drill core being in contact with said non-slip material.

Preferably, the two ends of the drill core are held by two mechanical drill core holding pistons, a deformable material, such as plasticine, silicone or neoprene, being placed between each end of the drill core and the associated mechanical piston.

According to the first embodiment of the present invention, the means for moving in translation are configured to move the support of lighting and imaging means in translation by sliding the latter along at least one guide rail parallel to the drill core support.

Thus, the means for moving in translation make it possible to move the support of lighting and imaging means along the guide rail, so as to allow the acquisition of the drill core over its entire length.

The control means make it possible to simultaneously control the means for displacement in rotation and in translation according to the first embodiment, so as to carry out, in a repeated manner, a 360° rotation of the drill core then a displacement of the support of means illumination and imaging of a certain step, until the complete scanning of the lateral surface of the drill core by the high-resolution imaging means and the hyperspectral imaging means.

According to a second embodiment of the present invention, the means for moving in rotation are configured to move in rotation the support of lighting and imaging means, said support of lighting and imaging means being a rotary crown disposed around the drill core support, the means for moving in rotation comprising a stepper motor configured to drive the rotary crown in rotation by means of a rack.

Thus, the stepper motor, controlled by the control means, makes it possible to drive the rotary crown in rotation by means of the rack arranged on one of the faces of the rotary crown, so as to allow the positioning of the lighting and imaging means carried by the rotary crown with respect to the drill core, to allow scanning of the drill core by the high-resolution imaging means and the hyperspectral imaging means.

According to a particular characteristic of the second embodiment of the present invention, the high-resolution imaging means, the hyperspectral imaging means and the lighting means are arranged on the inner face of the rotary crown, preferably in a distributed manner .

Thus, the lighting means, the high-resolution imaging means and the hyperspectral imaging means are oriented towards the drill core placed on the drill core support placed in the center of the rotating crown.

According to the second embodiment of the present invention, the means for moving in translation are configured to move the drill core in translation, the means for moving in translation comprising at least one conveyor belt arranged longitudinally in the drill core support. drilling and capable of receiving the drill core thereon, the at least one conveyor belt being configured to be driven in rotation by motorized pulleys so as to move the drill core along the drill core support.

Thus, the at least one conveyor belt, driven by the motorized pulleys, makes it possible to move the drill core along the drill core support, so as to allow the acquisition of the drill core over its entire length.

The control means make it possible to simultaneously control the means for displacement in rotation and in translation according to the second embodiment, so as to carry out, in a repeated manner, a 360° rotation of the support of lighting and imaging means around of the drill core then a displacement of the drill core on the drill core support by a certain pitch, until the complete scanning of the lateral surface of the drill core by the high resolution imaging means and the means of hyperspectral imaging.

The at least one conveyor belt makes it possible to absorb the vibrations during the movement of the drill core, the pulleys being mounted on ball bearings arranged in the drill core support to limit parasitic vibrations.

According to a particular characteristic of the second embodiment of the present invention, the drill core support is formed in two parts, namely an entry part and an exit part, said two parts being spaced apart from each other. another of a predefined spacing inside the rotary crown, each of said two parts comprising a conveyor belt inside the latter.

Thus, the predefined spacing between the two parts of the drill core holder makes it possible to scan the entire circumference of the drill core when the rotary crown is driven in rotation, so as to produce a three-dimensional model of the core drilling.

The predefined spacing between the two support parts is preferably a few centimeters and makes it possible to produce a 3D model in which the drill core support does not appear.

According to a particular feature of the present invention, the drill core support has the shape of a gutter capable of receiving a drill core wetting liquid.

Thus, the humidification liquid contained in the gutter-shaped carrot holder allows the humidification of the drill core during its analysis, the humidification liquid being able to be water or oil.

To better illustrate the object of the present invention, two preferred embodiments will be described below, by way of illustration and not limitation, with reference to the appended drawings.

In these drawings:

is a perspective view of a drill core analysis device according to a first embodiment of the invention;

is a perspective view from below of the lighting and imaging means support of the drill core analysis device of FIG. 1;

is a cross-sectional view of the drill core analysis device of Figure 1 at the level of the drill core;

is a perspective view of the entry face of a drill core analysis device according to a second embodiment of the invention;

is a perspective view of the exit face of the drill core analysis device of Figure 4; And

is a longitudinal sectional view of the drill core analysis device of Figure 4 at the level of the drill core.

Referring to Figure 1, it can be seen that there is shown a drill core analysis device 1 according to the first embodiment of the present invention.

The drill core analysis device 1 includes a drill core holder 2 configured to carry a drill core 3.

The drill core holder 2 comprises a gutter-shaped container 4 preferably containing a wetting liquid (not shown in Figure 1) and in which the drill core 3 is partially placed, the wetting liquid may be water or oil.

The drill core holder 2 further comprises two mechanical drill core holding pistons 5, the two ends of the drill core 3 being held by the two mechanical pistons 5, respectively, so as to hold the drill core 3 between the two mechanical pistons 5.

The drill core analysis device 1 further comprises two uprights 6 arranged on either side of the container in the form of a gutter 4.

Each mechanical piston 5 comprises a threaded rod 5a passing through one of the two uprights 6, said threaded rod 5a passing through a threaded nut 6a fixed to the corresponding upright 6, a circular piston head 5b fixed to the end of the threaded rod 5a between the two uprights 6, said piston head 5b being partially disposed in the gutter-shaped container 4, and a deformable material 5c fixed to the piston head 5b and capable of deforming when it is in contact with the associated end of the drill core 3, said deformable material being one of plasticine, silicone and neoprene.

Thus, the rotation of the threaded rod 5a in the corresponding threaded nut 6a allows the movement in translation of the mechanical piston 5, which makes it possible to approach the piston head 5b from the associated end of the drill core 3 in such a way to maintain the drill core 3 between the two mechanical pistons 5 at the level of the container in the form of a gutter 4.

The drill core analysis device 1 further comprises lighting means 7 configured to illuminate the drill core 3 and imaging means 8. The imaging means 8 comprise high resolution imaging means configured to perform high resolution imaging (≥ 20 megapixels) of drill core 3 and hyperspectral imaging means configured to perform hyperspectral imaging of drill core 3.

The lighting means 7 and the imaging means 8 are carried by a lighting and imaging means support 9 suspended on two guide rails 10 fixed between the two uprights 6, in the upper part thereof.

Although the high-resolution imaging means and the hyperspectral imaging means have been represented as a single imaging means 8 in FIG. 1, the high-resolution imaging means and the hyperspectral imaging means could also be distinct and arranged at two different locations on the lighting and imaging means support 9, without departing from the scope of the present invention.

The lighting means 7, the imaging means 8 and their support 9 will be described in more detail in Figure 2.

The drill core analysis device 1 further comprises rotational displacement means 11 (shown in Figures 1 and 3) configured to rotate the drill core 3.

The rotational displacement means 11 comprise three parallel rotary cylinders 12a, 12b and 12c arranged longitudinally in the container in the form of a gutter 4 and capable of receiving thereon the drill core 3.

The rotating cylinder 12a is arranged under the drill core 3, while the rotating cylinders 12b and 12c are arranged on either side of the circumference of the drill core 3.

Each rotating cylinder 12a, 12b and 12b is traversed by a rod 13a, 13b and 13c rotatably mounted in bearings 14 arranged in the container in the form of a gutter 4.

One of the ends of the rod 13a of the rotary cylinder 12a is rotatably mounted in a bearing 15 fixed to one of the uprights 6, while the other of the ends of the rod 13a of the rotary cylinder 12a is mounted in a motor motor 16 fixed to the other of the uprights 6. Thus, the rotary cylinder 12a is capable of being driven in rotation by the electric motor 16, which is preferably a stepper motor.

The ends of the rods 13b and 13c of the rotary cylinders 12b and 12c are, for their part, mounted in rotation in bearings 15 fixed to the two uprights 6.

The rotating cylinders 12a, 12b and 12c are preferably made of a non-slip material, such as neoprene, a rough band or a silicone fabric, the drill core 3 being in contact with said non-slip material.

Thus, the rotation of the rotary cylinder 12a, driven by the motor 16, causes the rotation of the drill core 3 on the three cylinders 12a, 12b and 12c, which allows the imaging, by the imaging means 8, of the entire circumference of the drill core 3.

Figure 2 shows in detail the lighting means 7, the imaging means 8 and their support 9.

The hyperspectral imaging means of the imaging means 8 comprise a hyperspectral camera 8a, but could also comprise several hyperspectral cameras 8a, without departing from the scope of the present invention.

The high-resolution imaging means of the imaging means 8 comprise a high-resolution camera (≥ 20 megapixels) of the reflex type 8a, but could also comprise several high-resolution cameras of the reflex or other type (for example, ATEX industrial camera, Module Connected Card Camera, etc.) or at least one high-resolution camera of the reflex or other type, without departing from the scope of the present invention.

As mentioned previously, the high resolution and hyperspectral cameras have been represented as a single camera 8a in Figure 2.

The lighting means 7 comprise an ultraviolet (UV) light source 7a and two white light sources 7b.

It should be noted that the lighting means 7 could also comprise any number of UV light sources 7a and any number of white light sources 7b, or only one or more UV light sources 7a, without departing from the scope of the present invention.

The UV light source 7a is capable of emitting, towards the drill core 3, an incident UV beam of different wavelengths, to illuminate the drill core 3 so as to characterize its mineralogical composition using the camera hyperspectral 8a, the energy of said incident UV beam being sufficient to cause the luminescence of the minerals of the drill core 3.

The UV light source 7a is either an optical fiber emission system calibrated in Bragg gratings, or a lamp calibrated in wavelength. The wavelengths of the UV incident beam are preferably the following: UV 365 nm, UV 254 nm, and optionally other wavelengths in the UV or infrared. It should be noted that an equivalent laser emission system could also be used, whatever the wavelength, without departing from the scope of the present invention.

Each white light source 7b comprises two series of light-emitting diodes 7c designed to illuminate the drill core 3 using an incident beam in the visible spectrum.

It should be noted that each white light source 7b could also comprise any number of series of light-emitting diodes 7c, without departing from the scope of the present invention. The white light source 7b could also be of the halogen or laser type, without departing from the scope of the present invention.

The support 9 of the lighting 7 and imaging 8 means comprises a first part 9a carrying the high resolution and hyperspectral cameras 8a and one of the two white light sources 7b and which is suspended from one of the two guide 10, and a second part 9b carrying the UV light source and the other of the two white light sources 7b and which is suspended from the other of the two guide rails 10.

Each of the first 9a and second 9b parts of the support 9 comprises a horizontal plate 17 on the upper face of which extend four vertical rods 18, the free end of each vertical rod 18 carrying a horizontal rotating wheel 19 cooperating with the rail of guide 10 corresponding so as to allow the sliding of said horizontal plate 17 along said guide rail 10, a first support arm 20, on which the high resolution and hyperspectral cameras 8a or the UV light source 7a is fixed, extending from the underside of the horizontal plate 17, and a second support arm 21, on which one of the two white light sources 7b is fixed, extending from the first support arm 20.

The drill core analysis device 1 further comprises means for moving in translation (not shown in Figures 1 to 3) configured to move in translation the support of lighting and imaging means 9 by sliding of that -ci along the guide rails 10 above the container in the form of a gutter 4. the support 9 along the guide rails 10, which allows the imaging, by the high resolution and hyperspectral cameras 8a, of the drill core 3 over the entire length of the latter.

The drill core analysis device 1 further comprises control means (not shown in Figure 1, arranged, for example, inside one of the uprights 6) configured to control the UV light sources 7a and white 7b, the high resolution and hyperspectral cameras 8a, the electric motor 16 of the rotary cylinder 12a and the electric motors of the rotary wheels 19 of the lighting and imaging means support 9, so as to implement a method drill core analysis comprising the following steps: performing a three-dimensional modeling of the drill core 3 by photogrammetry using high resolution and hyperspectral cameras 8a; and carrying out an analysis of the mineralogical composition of the surface of the drill core 3 using the light spectrum, measured by the hyperspectral camera 8a, emitted by the drill core 3 by luminescence in response to the lighting emitted by the UV light source 7a and white light sources 7b.

The control means can be constituted by a processor, a microprocessor, a microcontroller, a digital signal processing device (DSP), a programmable gate array (FPGA), an application-specific integrated circuit (ASIC), etc.

The drill core analysis device 1 further comprises a display device 22 disposed on the outer face of one of the two uprights 6 and connected to the control means, said display device 22 being configured to display the three-dimensional modeling and analysis of the mineralogical composition of the forge core 3 carried out by the control means.

The lighting means 7, the imaging means 8 and the display device 22 are connected to the control means in a wired or wireless manner.

The drill core analysis device 1 also comprises a keyboard 23, as a man-machine interface, arranged on a tablet 24 located under the display device 22, said keyboard 23 making it possible to control the display device 22 and the control means.

The control means thus make it possible to control simultaneously, automatically or semi-automatically, the means for displacement in rotation 11 of the drill core 3 and the means for displacement in translation of the support of lighting and imaging means 9 , so as to carry out, in a repeated manner, a 360° rotation of the drill core 3 then a displacement of the support of lighting and imaging means 9 by a certain pitch, until the complete scanning of the surface side of the drill core 3, which allows 3D modeling and characterization of the mineral composition of the entire lateral surface of the drill core 3 analyzed.

After each displacement caused by the means for displacement in rotation 11 and the means for displacement in translation of the support 9, the drill core 3, illuminated by the lighting means 7, is imaged by the high resolution and hyperspectral imaging means 8, so as to subsequently carry out the 3D modeling by photogrammetry and the characterization of the mineralogical composition using the light spectrum detected.

The high-resolution and hyperspectral cameras 8a make it possible, respectively, to simultaneously produce a high-resolution 3D model and a hyperspectral 3D model of the drill core, the high-resolution 3D model and the hyperspectral 3D model then being superimposed in post-processing.

The drill core analysis device 1 thus makes it possible to digitally save the information contained on the surface of the drill core 3 with a high resolution (preferably between 10 and 100 μm) in order to be able to subsequently carry out the majority of the analyzes non-destructively.

The 3D digital model produced has a higher level of detail than that of an observation under a magnifying glass during a conventional description, the magnification obtained making it possible to analyze images whose pixel size is, preferably, of the order of 10 µm.

The three-dimensional modeling produced by the control means is preferably a textured three-dimensional modeling. Thus, during the 3D modeling of the drill core 3 using the high resolution and hyperspectral cameras 8a, a texture is added to the 3D model of the drill core 3, said texture making it possible to represent the relief on the surface drill core 3.

The hyperspectral camera 8a, different from a multispectral or superspectral camera, is a camera allowing reading, in a range of wavelengths corresponding to the visible and near infrared domains (preferably, from 400 to 1000 nm, and up to 'at 2500 nm when several hyperspectral cameras are used), of a surface by a large number (preferably, greater than 100) of narrow (preferably, less than or equal to 10 nm) and contiguous spectral bands, which allows a high precision detection by measuring fine spectral variations.

The hyperspectral camera 8a thus makes it possible to detect the spectral response of each pixel of the sample analyzed over a wide spectrum according to bands with a minimum thickness, preferably of 2 nm.

The response thus obtained under UV light and natural light allows identification for each pixel of the mineralogical composition of the drill core 3.

Analysis of the mineralogical composition of drill core 3 is thus based on the principle of spectroscopy, i.e. the study of the emission spectrum of a mineral species compared to a known source for extract qualitative information on the composition of certain minerals (mainly and traces), databases of the reflectivity of different mineral species allowing the identification of minerals from the spectrum emitted.

The minerals contained in the drill core 3 being luminescent, the luminescence of these minerals, when they are illuminated by the lighting means 7, is thus used to characterize the mineralogical composition of the drill core 3, the hyperspectral camera 8a making it possible to capture the light spectrum emitted, by luminescence, by the minerals on the surface of the drill core 3 in the visible but also in the infrared. The hyperspectral camera 8a thus makes it possible to identify different mineral phases of similar chemical composition and which are under-exploited in classical geology.

The control means of the drill core analysis device 1 are configured to qualitatively analyze the mineralogical composition of the surface of the drill core 3 by comparing the light spectrum measured by the hyperspectral camera 8a with a database of light spectra predefined, and by determining the mineral species present on the surface of the drill core 3 using said comparison.

Thus, the database of predefined light spectra, stored in a memory of the analysis device 1, contains all the existing hyperspectral data concerning the luminescence of different mineral species. The light spectrum detected by the hyperspectral camera 8a can thus be compared with the data contained in said database in order to determine which mineral species make up the drill core 3. This implies cross-referencing the data acquired for each mineral at each length d wave through recognition algorithms using neural networks.

The control means of the drill core analysis device 1 are further configured to semi-quantitatively analyze the mineralogical composition of the surface of the drill core 3 by determining the quantity of each mineral species present on the surface of the core drilling 3, by determining the number of common spectra.

Thus, the analysis of the light spectrum detected by the hyperspectral camera 8a also makes it possible to determine the quantity of each of the mineral species detected.

The analysis device 1 thus makes it possible to carry out both a qualitative and semi-quantitative analysis of the minerals, of their polymorphs (same chemical formula but different mineralogical assembly), by identifying certain trace elements (concentration of the order of 100- 1000 ppm or more).

The drill core analysis device 1 is preferably designed to be removable and easily transportable on a drilling platform.

Referring to Figures 4 to 6, it can be seen that there is shown a drill core analysis device 100 according to the second embodiment of the present invention.

The common elements between the first embodiment of the invention in Figures 1 to 3 and this second embodiment of the invention bear the same reference number to which 100 has been added except for the core analysis device of drilling referenced 100, and will not be described in more detail here when they are of identical structures.

The drill core support 102 of the drill core analysis device 100 is formed in two aligned parts 104a and 104b, namely a gutter-shaped inlet part 104a and a gutter-shaped outlet part 104b, said two parts 104a and 104b being spaced apart by a predefined spacing.

Each of the first and second parts in the form of gutter 104a and 104b is fixed on a vertical foot 125 itself fixed on a base 126.

The support 109 of the lighting means 107 and the imaging means 108 is a rotating crown 127 arranged around the drill core support 102.

The rotating crown 127 is made up of two parallel rings 127a interconnected by a hollow cylinder 127b, the axes of the two rings 127a and of the hollow cylinder 127b being identical and horizontal.

The predefined spacing between the two gutter-shaped parts 104a and 104b of the drill core holder 102 is located inside the rotary crown 127, in the hollow cylinder 127b.

The imaging means 108 include a hyperspectral camera 108a, but could also include several hyperspectral cameras 108a, without departing from the scope of the present invention.

The imaging means 108 further comprise a high resolution camera (≥ 20 megapixels) of the reflex type 108a, but could also comprise several high resolution cameras of the reflex or other type (for example, ATEX industrial camera, Connected Card Camera Module, etc. .) or at least one high-resolution camera of the reflex or other type, without departing from the scope of the present invention.

As previously indicated, the high resolution and hyperspectral cameras have been shown as a single camera 108a in Figures 4-6.

The lighting means 107 include a UV light source 107a, but could also include several UV light sources 107a, and/or one or more white light sources, without departing from the scope of the present invention.

The high resolution and hyperspectral cameras 108a and the UV light source 107a are fixed through the hollow cylinder 127b of the rotating crown 127, so that they all point towards the center of the rotating crown 127 and therefore towards the core of drilling 103 when part of the latter is located inside the rotary crown 127.

The UV light source 107a is able to emit, towards the drill core 103, an incident UV beam of different wavelengths, to illuminate the drill core 103 so as to characterize its mineralogical composition using the camera hyperspectral 108a, the energy of said incident UV beam being sufficient to cause the luminescence of the minerals of the drill core 103.

The UV light source 107a is either a fiber optic emission system calibrated in Bragg gratings, or a lamp calibrated in wavelength. The wavelengths of the UV incident beam are preferably the following: UV 365 nm, UV 254 nm, and optionally other wavelengths in the UV or infrared. It should be noted that an equivalent laser emission system could also be used, without departing from the scope of the present invention.

The rotational displacement means 111 of the drill core analysis device 100 are configured to rotate the rotary crown 127 carrying the high-resolution and hyperspectral cameras 108a and the UV light source 107a.

The rotational displacement means 111 comprise an additional rotary crown 128 whose diameter is greater than that of the rotary crown 127, the rotary crown 127 being positioned at the center of the additional rotary crown 128 using three holding arms 129 .

The entry face of the additional rotary crown 128 facing the entry part 104a of the drill core support 102 carries a guide rail 128a resting on two bearings 130 arranged on either side of the guide rail 128a under the center of gravity of the additional rotary crown 128 to support its weight, each bearing 130 being fixed on an upright 131 itself fixed on the base 126.

The uprights 131 are preferably telescopic to allow the disassembly and transport of the additional rotary crown 128 and of the entire analysis device 100.

The entry face of the additional rotary crown 128 opposite the entry part 104a of the drill core holder 102 also carries a rack 132.

The rotational displacement means 111 further comprise a stepper motor 133 whose shaft carries a gear 133a engaged with the rack 132, said stepper motor 133 thus being configured to drive the additional rotary crown 128 in rotation by through the rack 132 and thus to rotate the rotary crown 127.

Thus, the stepper motor 133 controlled by the control means of the drill core analysis device 100, makes it possible to drive the rotary crown 127 in rotation so as to allow the positioning of the high resolution and hyperspectral cameras 108a and to the UV light source 107a carried by the rotary crown 127 with respect to the part of the drill core 103 located inside the rotary crown 127, in order to allow three-dimensional scanning of the drill core 103 by the high cameras resolution and hyperspectral 108a.

The predefined spacing between the two parts 104a and 104b of the drill core support 102 makes it possible to scan the entire circumference of the drill core 103 when the rotary crown 127 is driven in rotation, so as to produce a three-part model. dimensions of drill core 103.

The predefined spacing between the two parts 104a and 104b is preferably a few centimeters and makes it possible to produce a 3D model in which the drill core support 102 does not appear.

The means for moving in translation 134 of the drill core analysis device 100 are configured to move the drill core 103 in translation in the drill core holder 102.

The means for moving in translation 134 comprise, in each of the two parts 104a and 104b of the drill core support 102, a conveyor belt 135 arranged longitudinally in said respective part 104a, 104b and capable of receiving the drill core thereon. drilling 103.

Each conveyor belt 135 is configured to be rotated by motorized pulleys 136 so as to move the drill core 103 along the drill core support 102, from the entry part 104a to the exit part 104b, from such that the drill core 103 crosses the rotary crown 127 so as to allow imaging by the high resolution and hyperspectral cameras 108a of the drill core 103 over its entire length.

The conveyor belts 135 make it possible to absorb the vibrations during the displacement of the drill core 103, the pulleys 136 being mounted on ball bearings arranged in the drill core support 102 to limit parasitic vibrations.

The control means (not shown, arranged, for example, in the additional rotary crown 128) of the drill core analysis device 100 are configured to control the UV light source 107a, the high resolution and hyperspectral cameras 108a, the stepper motor 133 of the means for moving in rotation 111 and the motorized pulleys 136 of the conveyor belts 135, so as to implement the method for analyzing the drill core comprising the following steps: performing a three-dimensional modeling of the drill core drilling 103 by photogrammetry using high resolution and hyperspectral cameras 108a; and performing an analysis of the mineralogical composition of the surface of the drill core 103 using the light spectrum, measured by the hyperspectral camera 108a, emitted by the drill core 103 by luminescence in response to the illumination emitted by the UV light source 107a.

In particular, the control means make it possible to control simultaneously, automatically or semi-automatically, the means for displacement in rotation 111 and the means for displacement in translation 134, so as to carry out, in a repeated manner, a rotation through 360° of the rotary crown 127 around the drill core 103 then a displacement of the drill core 103 on the drill core support 102 by a certain pitch, until the complete scanning of the lateral surface of the drill core 103 , which allows 3D modeling and characterization of the mineral composition of the entire lateral surface of the drill core 103 analyzed.

The control means can be constituted by a processor, a microprocessor, a microcontroller, a digital signal processing device (DSP), a programmable gate array (FPGA), an application-specific integrated circuit (ASIC), etc.

The display device 122, placed on a shelf 137 raised by a foot 138, is connected to the control means and configured to display the three-dimensional modeling and the analysis of the mineralogical composition of the forge core 103 produced by the means of order.

The lighting means 107, the imaging means 108 and the display device 122 are connected to the control means in a wired or wireless manner.

In the case of a wired connection, the output face of the additional rotary crown 128 opposite the part 104b of the drill core holder 102 carries a circular connection shoe (not shown in Figures 4 to 6), the all of the signals originating from the high resolution and hyperspectral cameras 108a being amalgamated via a multiplexing cell connected to said pad, the pad being engaged in an output rail connected to an acquisition unit containing a demultiplexing cell configured to rearrange the signals into a separate, identified data set.

The drill core analysis device 100 also includes a keyboard 123, as a man-machine interface, placed on the tablet 137, said keyboard 123 making it possible to control the display device 122 and the control means.

After each displacement caused by the means for displacement in rotation 111 and the means for displacement in translation 134, the drill core 103, illuminated by the lighting means 107, is imaged by the high resolution and hyperspectral imaging means 108, so as to carry out, thereafter, the 3D modeling by photogrammetry and the characterization of the mineralogical composition using the detected light spectrum.

The drill core analysis device 100 thus makes it possible to digitally save the information contained on the surface of the drill core 103 with a high resolution (preferably, between 10 and 100 μm) in order to be able to subsequently carry out the majority of the analyzes non-destructively.

The three-dimensional modeling produced by the control means is preferably a textured three-dimensional modeling. Thus, during the 3D modeling of the drill core 103 using the high resolution and hyperspectral cameras 108a, a texture is added to the 3D model of the drill core 103, said texture making it possible to represent the relief on the surface. drill core 103.

The hyperspectral camera 108a, different from a multispectral or superspectral camera, is a camera allowing reading, in a range of wavelengths corresponding to the visible and near infrared domains (preferably, from 400 to 1000 nm, and up to 'at 2500 nm when several hyperspectral cameras are used), of a surface by a large number (preferably, greater than 100) of narrow (preferably, less than or equal to 10 nm) and contiguous spectral bands, which allows a high precision detection by measuring fine spectral variations.

The hyperspectral camera 108a thus makes it possible to detect the spectral response of each pixel of the sample analyzed over a broad spectrum according to bands with a minimum thickness, preferably 2 nm. The response thus obtained under UV light allows identification for each pixel of the mineralogical composition of the drill core 103.

The control means of the drill core analysis device 100 are configured to qualitatively analyze the mineralogical composition of the surface of the drill core 103 by comparing the light spectrum measured by the hyperspectral camera 108a with a database of light spectra predefined, and by determining the mineral species present on the surface of the drill core 103 using said comparison.

The predefined luminous spectra database, stored in a memory of the analysis device 100, contains all the existing hyperspectral data concerning the luminescence of various mineral species. The light spectrum detected by the hyperspectral camera 108a can thus be compared with the data contained in said database in order to determine which mineral species make up the drill core 103.

The control means of the drill core analysis device 100 are further configured to semi-quantitatively analyze the mineralogical composition of the surface of the drill core 103 by determining the quantity of each mineral species present on the surface of the core drilling 103, by determining the number of common spectra.

The analysis device 100 thus makes it possible to carry out both a qualitative and semi-quantitative analysis of the minerals, of their polymorphs (same chemical formula but different mineralogical assembly), by identifying certain trace elements (concentration of the order of 100- 1000 ppm or more).

The drill core analysis device 100 is preferably designed to be removable and easily transportable on a drilling platform.

It is understood that the two particular embodiments which have just been described have been given as an indication and not limiting, and that modifications can be made without departing from the present invention.

Claims (16)

Method for analyzing a drill core (3; 103), characterized in that it comprises the following steps:
- performing a three-dimensional modeling of the drill core (3; 103) by photogrammetry using high resolution imaging means (8; 108) and hyperspectral imaging means (8; 108); And
- carrying out an analysis of the mineralogical composition of the surface of the drill core (3; 103) using the light spectrum, measured by the hyperspectral imaging means (8; 108), emitted by the drill core ( 3; 103) by luminescence in response to lighting emitted by lighting means (7; 107). Method of analyzing a drill core (3; 103) according to claim 1, characterized in that the three-dimensional modeling is a textured three-dimensional modeling. Method for analyzing a drill core (3; 103) according to one of Claims 1 and 2, characterized in that the analysis of the mineralogical composition of the surface of the drill core (3; 103) comprises the comparison of the light spectrum measured by the hyperspectral imaging means (8; 108) with a database of predefined light spectra, and the determination of the mineral species present at the surface of the drill core (3; 103) using said comparison. Method for analyzing a drill core (3; 103) according to claim 3, characterized in that the analysis of the mineralogical composition of the surface of the drill core (3; 103) further comprises determining the quantity of each mineral species present on the surface of the drill core (3; 103). Method of analyzing a drill core (3; 103) according to one of Claims 1 to 4, characterized in that the illumination emitted by the illumination means (7; 107) is at least one of ultraviolet light, white light and monochromatic laser light. Drill core analysis device (1; 100), characterized in that it comprises:
- a drill core holder (2; 102) configured to carry a drill core (3; 103);
- lighting means (7; 107) configured to illuminate the drill core (3; 103);
- high resolution imaging means (8; 108) configured to perform high resolution imaging of the drill core (3; 103);
- hyperspectral imaging means (8; 108) configured to perform hyperspectral imaging of the drill core (3; 103);
- a support for lighting and imaging means (9; 109) carrying the lighting means (7; 107), the high-resolution imaging means (8; 108) and the hyperspectral imaging means (8 ;108);
- means for moving in rotation (11; 111) configured to move in rotation one of the drill core (3; 103) and the support of lighting and imaging means (9; 109);
- means for moving in translation (134) configured to move in translation one of the drill core (3; 103) and the support of lighting and imaging means (9; 109); And
- control means configured to control the lighting means (7; 107), the high resolution imaging means (8; 108), the hyperspectral imaging means (8; 108), the rotation displacement means (11; 111) and the means for moving in translation (134), so as to implement the method for analyzing drill core according to one of Claims 1 to 5. Drill core analysis device (1; 100) according to claim 6, characterized in that the hyperspectral imaging means (8; 108) comprise at least one hyperspectral camera (8a; 108a). Drilling core analysis device (1; 100) according to one of Claims 6 and 7, characterized in that the high-resolution imaging means (8; 108) comprise at least one of a high-resolution camera resolution and a high resolution camera such as an SLR. Drill core analysis device (1; 100) according to one of Claims 6 to 8, characterized in that it further comprises a display device (22; 122) connected to the control means, said display device (22; 122) being configured to display the three-dimensional modeling and the analysis of the mineralogical composition of the forge core (3; 103) carried out by the control means. Drilling core (1) analysis device according to one of Claims 6 to 9, characterized in that the means of displacement in rotation (11) are configured to move the drilling core (3) in rotation, and comprise at least three parallel rotating cylinders (12a, 12b, 12c) arranged longitudinally in the drill core holder (2) and capable of receiving thereon the drill core (3), at least one ( 12a) of the at least three rotary cylinders (12a, 12b, 12c) being capable of being driven in rotation by a stepping motor (16). Drill core analysis device (1) according to one of Claims 6 to 10, characterized in that the means for moving in translation are configured to move the support of lighting and imaging means ( 9) by sliding it along at least one guide rail (10) parallel to the drill core support (2). Drill core analysis device (100) according to one of Claims 6 to 9, characterized in that the means of displacement in rotation (111) are configured to displace in rotation the support of lighting means and imagery (109), said support of lighting and imaging means (109) being a rotating crown (127) arranged around the drill core support (102), the rotational displacement means (111) comprising a stepper motor (133) configured to drive the rotary crown (127) in rotation via a rack (132). Drill core analysis device (100) according to Claim 12, characterized in that the high-resolution imaging means (108), the hyperspectral imaging means (108) and the lighting means (107) are arranged on the inner face of the rotary crown (127), preferably in a distributed manner. Drill core analysis device (100) according to one of Claims 6, 7, 8, 9, 12 and 13, characterized in that the means for moving in translation (134) are configured to move in translation the drill core (103), the means for moving in translation (134) comprising at least one conveyor belt (135) arranged longitudinally in the drill core support (102) and capable of receiving thereon the drill core (103), the at least one conveyor belt (135) being configured to be driven in rotation by motorized pulleys (136) so as to move the drill core (103) along the drill core support (102 ). Drill core analysis device (100) according to claim 14, characterized in that the drill core support (102) is formed in two parts (104a, 104b), namely an entry part (104a ) and an output part (104b), said two parts (104a, 104b) being spaced from each other by a predefined spacing inside the rotary crown (127), each of said two parts (104a , 104b) including a conveyor belt (135) therein. Drill core analysis device (1; 100) according to one of Claims 6 to 15, characterized in that the drill core support (2; 102) has the shape of a gutter capable of receiving a liquid from drilling core humidification.